In the manufacture of printed circuit boards, printed circuit elements and like goods, and in processes connected with the same, it has become commonplace to deliver the articles, such as printed circuit boards, printed circuit film or the like, through a chamber in a continuous manner, while the articles are being treated by the spray of a suitable treatment fluid, such as an etchant, onto them. Often the etchant is of a corrosive nature, but on other occasions it can be various chemical solutions or even ordinary rinsing liquid, such as water. See, for example, U.S. Pat. No. 4,233,106, the disclosure of which is herein incorporated by reference.
Especially in instances when the treatment fluids are liquids that are corrosive in nature, it is undesirable to have the liquids pass outwardly of the treatment chamber, because if they did, they would require earlier replenishment than would be desirable, or would require special handling of the treatment liquid that passes outwardly of the chamber. Even further, considerations of costs are involved, in connection with loss of treatment fluid.
In the course of preventing the passage of treatment fluid outwardly of treatment chambers, it has become commonplace to locate a pair of opposed rollers, at least near the exit of the treatment chamber, although in many instances opposed pairs of rollers are located at both the inlet and exit of the treatment chamber, preventing the undesirable passage of treatment liquid out an associated opening of the chamber. In even other instances, opposed roller pairs are provided at various locations throughout the treatment chamber, not related to an opening.
In any event, opposed roller pairs are utilized in treatment chambers to prevent passage of liquid out openings, or to provide a driving means for driving the articles that are treated along their predetermined path through the chamber, generally from inlet to exit, or to both drive the articles and prevent liquid passage.
In the course of known processes, it has been commonplace for rollers to provide a nip between them for squeezing the articles as they pass through the nip, to facilitate removal of the treatment liquid from surfaces of the articles as they pass through the nip. Such rollers are generally referred to as anti-dragout rollers, because they cooperate to prevent the dragging-out of treatment liquid from the chamber at the exit end.
It will be understood that similar, although perhaps less pronounced problems can exist at the inlet end of the chamber, so that similar rollers are often used thereat.
With increased miniaturization in many industries, including the electronics industry, printed circuit articles have become thinner and thinner, such that they are more flexible or film-like than theretofore. The same is true of articles treated with other treatment fluids, not involved with the printed circuit industry.
As articles being treated become increasingly thinner, upon their passing through a nip of opposed rollers, they have a tendency to adhere to the surface of one of the rollers after passing through the nip, and thereafter tend to follow that surface of the rollers such that they leave the predetermined path of travel for such articles and curve around a roller. Often, this is due to the presence of a small amount of treatment liquid that remains on the roller surface and on the article being treated, downstream of the nip, that is sufficient to cause the article and roller surface to adhere together at that point.
Accordingly, the path of travel of articles being treated can be interrupted. This can be especially troublesome in the operation of a continuous process, whereby the operation may become interrupted.
The present invention is directed toward affecting the treatment of articles as described above, in such a way that as articles pass through the nip of an opposed pair of rollers, they are engaged as they pass downstream of the nip and are urged away from a surface of the roller, such that thin, flexible articles emerging from the nip are restrained from adhering to the surface of the roller, whereby wrap-around of the articles relative to the roller can be avoided.